Silicon pressure sensors offer multiple benefits that include small size, good quality, and stable performance. Further, since multiple identical sensors can be fabricated simultaneously on a single wafer, silicon pressure sensors are also cost effective to manufacture. In at least one example of a pressure sensor, piezo-resistive silicon structures are fabricated on a diaphragm such that the piezo-resistive structures sense the strain in the diaphragm as the diaphragm reacts to pressure applied by the pressure media. However, strain caused by the support structures of the diaphragm may cause changes in sensor output. Some of the materials used to manufacture the support structures may be hygroscopic. When the support structures are hygroscopic, the physical size of the support structures change as the support structures absorb moisture in the air. The change in physical size changes the stress on the diaphragm, which commensurately changes sensor output and causes sensing errors.
In addition, when the pressure sensor is used to measure the absolute pressure in an environment, a stable reference vacuum may be provided around a side of the sensor's pressure sensing diaphragm that is opposite to the side of the sensing diaphragm that is exposed to a pressure media. Over time, materials in the reference vacuum can outgas. The out gassing of materials within the reference vacuum change the pressure difference between different sides of the diaphragm which causes drift errors in sensor measurements.